Blade lock



sept. 12, 1967 F. B. MANNING Y BLADE LOCK Filed Feb. 27, 1967 United States Patent O 3,341,174 BLADE LOCK Frank B. Manning, Vernon, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed Feb. 27, 1967, Ser. No. 618,963 9 Claims. (Cl. 253-77) ABSTRACT OF THE DISCLOSURE A turbomachine having Ia rotor assembly construction wherein a deformable blade lock is inserted into the blade root thereby preventing any axial movement of the blade in the rotor disc.

Background of the invention This invention relates to a rotor assembly for use in a turbomachine and more particularly to a blade lock therein.

It is obvious that in a turbomachine some arrangement must be provided to hold lor lock lthe blades in place in the rotor assembly. Probably the most common method of retaining blades in a turbine which is employed by the prior art is the use of a pin which extends in la generally radial direction through the wheel int-o the base of the blades. The most common method of retaining blades in a compressor which is employed by the prior art is the use of keys or tablocks which lie beneath the root of the blades at the bottom of the blade slots and are fixed to the wheel and blade.

While these and other similar locking devices provide adequate blade retention, they have a number of inherent disadvantages. For example, the pin-type locking device weakens the wheel at a point of very high stress with the result that the entire wheel must be made heavier than would otherwise be necessary, and this type of locking device tends to reduce the tangential blade tip wobble when the assembly is cold. The key or blade lock retention is weak in the axial direction with the result that the blades may walk out of the wheel slots.

Summary of invention It is a primary object of this invention to provide a rotor assem-bly with a stronger and improved blade lock which is readily applied and removed while providing for the -desired blade tip movement and not weakening the rotor disc.

The present invention relates to a deformable U-shaped blade lock. The rotor `assembly which uses this blade lock contains la blade which when inserted in the rotor disc slot is prevented from moving axially in one direction by either stop means on the blade root or cooperating stop means on the blade and disc. After insertion of the blade, one end of the blade extends axially beyond the rotor disc. The blade root, at this end, contains two passages which extend in a plane generally parallel to the plane of the disc and these passages in the root are in generally abutting relationship to the rotor disc. These passages are oblique with respect to one another, the openings of the passages being chamfered to facilitate insertion of the U-shaped -blade lock. As the U-shaped lock is inserted, the legs of the U are forced to follow the oblique passages, this deformation thereby preventing the blade lock from falling out. Once inserted, the U-shaped blade lock in cooperation with the stop means previously mentioned prevent any axial movement of the blade.

It is of significance that the U-shaped blade lock extends only into or through the blade root and not into the blade disc. This construction thereby permits removal r 3,341,174 Patented Sept. 12, 1967 Brief description of the drawings FIGURE 1 is a fragmentary sectional view of a rotor assembly showing the device of the invention thereof.

FIGURE 2 is a view of the U-shaped blade lock in the nondeformed unassembled state.

FIGURE 3 is a fragmentary side view of a rotor assembly showing the device of the invention thereof.

Description of the preferred embodiment Referring rst to FIGURE 1 for a description of an illustrative embodiment of the invention, a compressor rotor 10 supports a series of radially extending blades 12 mounted in peripheral slots 14 extending from the rear or first face 16 of the rotor to its forward or second face 18 in a direction substantially axial with respect to the general disposition of the rotor.

Each blade 12 includes a root section 20 and in the embodiment illustrated, root section 20 has a radially inwardly extending flange 22 which abuts against rst face 16, thereby effectively preventing axial movement of the blade in one direction. The end of blade root opposite ange 22 contains two oblique passages 24. Passages 24 are oblique with respect to one another and are positioned within blade root 20 such that the plane of passages 24 are generally parallel to the plane of rotor disc 10. Passages 24 are positioned within root 20 such that when blade lock 26 is inserted in the passages, the extending portions of blade lock 26 abut against second 4face 18 of rotor disc 10. FIGURE 3 clearly illustrates this description.

Blade lock 26 is a deformable U-shaped member and is illustrated in its nondeformed state in FIGURE 2. Legs 28 of the U-shaped member are inserted into passages 24 and as the legs are pushed through passages 24, the U- shaped member deforms, this deformation then preventing the blade lock from falling out of the blade root 20. Legs 28 preferably are made longer than passages 24 so that before the -blade lock can fall out, as the result of a failure, blade lock 26 must shear infour separate places. Blade lock 26 when fully inserted into passages 24, in cooperation with flange 22, prevents axial movement of blade 12. The arcuate portion 30 of the U-shaped member is used as the means for withdrawing blade lock 26 from passages 24.

I claim:

1. A rotor assembly for a turbomachine comprising a disc having blade receiving slots in the periphery thereof extending generally axially from the first side of said disc to the second side, and removable blades including a root portion slidably mounted in said slots, wherein the improvement comprises:

one end of said root portion having stop means, the

stop means abutting said first side of said disc, the root end remote therefrom extending axially beyond said slot, said axially extending end having at least two passages positioned obliquely with respect to one another, said passages extending generally parallel to the plane of said disc and being in abutting relationship to said second side of said disc;

and a deformable, substantially U-shaped member eX- tending into said oblique passages, the portions of said U-shaped member which extend from said oblique passages beyond said root end abutting said second side of said disc so that said blade cannot -move Iaxially after said U-shaped member is inserted. 2. A construction as in claim 1 in which: the legs of said U-shaped member are longer than said oblique passages so that the arcuate portion of said U-shaped member and the ends of said legs abut against said second side of said disc.

3. A construction as in claim 1 in which:

the arcuate portion of said U-shaped member extends beyond said oblique passages so that said U-shaped member may be withdrawn from said oblique passages by applying a retracting means to said arcuate portion.

4. A construction as in claim 1 in which:

the legs of said U-shaped member extend in an outward direction relative to the center of said disc and the base of the U extends in an inward direction relative to the center of said disc.

5. A construction as in claim 1 in which:

said stop means comprises a radially inwardly extending projection, said projection abutting said rst side of said disc.

`6i. A construction as in claim 1 in which:

t-he cross-section area of said oblique passages is substantially the same as the cross-section area of said legs of said U-shaped member.

7. A rotor assembly for a turbomachine comprising a disc having blade receiving slots in the periphery thereof extending generally axially from one face of the disc to the opposite face of said disc, and removable blades including a root portion slidably mounted in said slots, wherein the improvement comprises:

said root portion yand said disc member having cooperating stop means to prevent axial movement in one direction, one end of said root portion extending axially beyond said slot, said axial extending end having at least two passages positioned obliquely with respect to one another, said passages extending generally parallel to the plane of said disc and being in abutting relationship to said disc; and

a deformable substantially U-shaped member extending into said oblique passages, the portions of said U- shaped member which extend from said oblique passages beyond said root end abutting said disc so that said blade cannot move axially after insertion of said U-shaped member. 8. A construction as in claim 7 in which: the legs of said U-shaped member are longer than said oblique passages so that the arcuate portion of said U-shaped member and the ends of said legs abut against said disc. 9. A construction as in claim 7 in which: the legs of said U-shaped member extend in an outward direction with respect to the center of said disc and the base of the U extends in an inward direction relative to the center of said disc.

References Cited UNITED STATES PATENTS 2,755,062 7/1956` Hill 253-77 2,781,962 2/ 1957 Wilder 253-77 X 2,953,348 9/1960 Leland 253--77 MARTIN P. SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, IR., Examiner. 

1. A ROTOR ASSEMBLY FOR A TURBOMACHINE COMPRISING A DISC HAVING BLADE RECEIVING SLOTS IN THE PERIPHERY THEREOF EXTENDING GENERALLY AXIALLY FROM THE FIRST SIDE OF SAID DISC TO THE SECOND SIDE, AND REMOVABLE BLADES INCLUDING A ROOT PORTION SLIDABLY MOUNTED IN SAID SLOTS, WHEREIN THE IMPROVEMENT COMPRISES: ONE END OF SAID ROOT PORTION HAVING STOP MEANS, THE STOP MEANS ABUTTING SAID FIRST SIDE OF SAID DISC, THE ROOT END REMOTE THEREFROM EXTENDING AXIALLY BEYOND SAID SLOT, SAID AXIALLY EXTENDING END HAVING AT LEAST TWO PASSAGES POSITIONED OBLIQUELY WITH RESPECT TO ONE ANOTHER, SAID PASSAGES EXTENDING GENERALLY PARALLEL TO THE PLANE OF SAID DISC AND BEING IN ABUTTING RELATIONSHIP TO SAID SECOND SIDE OF SAID DISC; AND A DEFORMABLE, SUBSTANTIALLY U-SHAPED MEMBER EXTENDING INTO SAID OBLIQUE PASSAGES, THE PORTIONS OF SAID U-SHAPED MEMBER WHICH EXTEND FROM SAID OBLIQUE PASSAGES BEYOND SAID ROOT END ABUTTING SAID SECOND SIDE OF SAID DISC SO THAT SAID BLADE CANNOT MOVE AXIALLY AFTER SAID U-SHAPED MEMBER IS INSERTED. 